The invention is concerned with a process and apparatus for testing the integrity of filter elements which are located in protected environments, such as clean rooms, sterile rooms, explosion-proof rooms, and production areas for products in the areas of microelectronics, biotechnology, foodstuffs, pharmaceuticals, medicines and chemicals.
Testing the integrity of filter elements includes tests of pressure retention, diffusion rates, water intrusion, and the determination of bubble points. Filter elements to be tested include flat filters, hollow fiber filters, and tubes. The form of the filters include cartridges, capsules, and disposable and cassette modules, and may include hydrophobic and hydrophilic membranous filters or woven fleece-like fabric as used in the areas of ultrafiltration and microfiltration.
Conventional testing of the integrity of filter elements is often carried out with automatic test devices, which are joined to the filter elements and to a pressurized gas source. Such automatic test devices are commercially available, for example, from Sartorius AG of Goettingen, Germany as the "Sartocheck" tester. To test the integrity of a filter, one side of the filter is pressurized by a test gas at a designated test pressure. After stabilization, pressure changes are measured on either the pressurized or the unpressurized side of the filter over a predetermined time interval. From the values computed by the filter test equipment from the test data, a report is printed out detailing the status of the integrity of the filter, including a report on whether failure of the filter element is imminent.
When performing conventional integrity tests on filter elements in protected environments, the filter test equipment remains outside the room to avoid contamination. The pressure test line from the test device to the filter element goes through the wall or the ceiling of the room and is connected to the filter element at a point proximate the entry of the line through the wall or ceiling. When a test is to be done, a person inside the protected environment signals the operator of the filter test device outside the room, who conducts the test and then informs the person in the room whether or not the filter has passed the tests. However, this method requires considerable expense to install contamination-proof test lines through the wall or ceiling. A further drawback is that two persons are required, and miscommunications can and frequently do occur.
There is therefore a need in the art for a simplified, less expensive filter testing system that avoids the foregoing shortcomings. This need and others which will become apparent, are summarized and described in detail below.